Dental prosthesis



.Mawh 1954 G. s. A. DAHL ETAL DENTAL paosmzszs Filed NOV. 12, 1949 WoMV- Lm QM;

44 Cw g mnw Patented Mar. 23, 1954 UN ITE D STATES PATENT OFFICE;

' Gustav -Sventldolf Dahl and Sven BertilAlmr, Stockholm, SwedenApplication November-lfl, 1949,1LSerialNo'. 126F66 Claimsmriority,application Sweden November 15, .1948.

(Cli 32 10) 5 Claims.

.The present inventionrelates. to .dental prostheses; and moreparticularlyflto those which consistofa supporting bodyof metal,generally'gold, and'ajfacing .or. a similar toothimitation of anartificial material, i previously usually porcelain.

butJnoWadays alsoartificial resin, such as acrylic resin,'themetallic'support being intended to form an attachmentwithin or at thesideof the existingteeth and thefacingbeingadapted to give theprosthesis .a naturalappearance, especially.

on the outwards directed or otherwise visible part oftthe prosthesis;"Examples of prostheses of .the presentkind are particularly so-calledbridges where the prosthesis is suspended to adjacent.

teeth, and pivot teeth. where the prosthesis is an-. chored in aremaining natural root of a tooth Iii-"hitherto occurring typ esflofprostheses of the present kind the metallicbody'is usually providedwith'projections which. accurately fit" in corre sponding recessesprovided in the facing; These connectingxmembers. have been so designedthat the" facing could be applied "to" the supporting body inauuitedefinitedirection only, which has been considered to be necessarywiththe previously available possibilities of. obtaining a firm andrigidconnection between'theseparts. For.

thejunction there has been employed; besides the purely'mechanicalanchoring "means, a binding agent OfIOI'dll'lBiIYfklIId, e. g. phosphatecement, whetherthe' facing has beenmadeof porcelain or of'artificialresin. Incase of artificial resin prostheses :ithas,.moreover, beenusual to producethe prosthesis by "moulding the facing from theartificial resin compound and pressing it directly ,onto the metallicsupport. and then subjectingit to final treatment, usually anoperationof polymerization, at an elevated temperature.

However, it has been :found that, inconnection withdental prosthesesconsisting ofmetallic body with retentions and facing or similartoothimitation..made of soluble artificiahresin preferably acrylicresin, itis. possible tolbring about. a much easier method ofapplying thefacingand to-ob tain .at thesame time; a. considerably betterconnectionbetween .the parts, .,:'j.f'. the facing tor. thelikel'isrsecuredto the, metallic. body byrmeans. of I a -binding agent;meltedtogether with the facing by;means .of a-solvent or'a plasticizer;such as ethyl acetate or preferably chloroform,-said bindingagent beingsuitably produced onathebasisof artificiaL-resin preferably; fromtheisame; artifiw ciahresin,basalsmateriallas the facing; Prefene ablythe inside of the facing is so designed that the facing may,notwithstanding. the. retentions. of the metallic body, be applied intoits finallposia tion onto the, metallic body from a pluralitymfdiiferent directions.

final position has been reached orhasbeennearlyi reached.

The invention will be more.closely.described, in the following withreference to some. realiza=. tions shown in the accompanyingdrawingmerelyi as illustrative examples and not inla limiting sense, andin addition comparisonsare madeiwithj previously known arrangementsintended for the. same purpose.

In the drawing; Figures 1' to 5.show embodi ments according tothe-invention, Figures 1. and .4 showing facings disposed on bridges,Figures, 2.

and 5 showing the facings proper, as viewed from the inside, and Figure3 shows the facinggof Figures 1 and 2 adapted fora pivot tooth.

According to the present invention there is emplayed a binding agentwhich bindsfirmlyito the facing, preferably one having substantially.the

same elastic propertiesas the facing material,

and, as a result; newpromising possibilities present themselves: Apreferred binding agent consists-of a syntheticresin polymer, suitably,of. acrylic resin, such as polymethyl metha.crylate,.

dissolved by or at leastswelled up withQa solvent amine in. appropriateconcentrations;

will. have imperceptibly passed over; intimately and: without any seam,into the material-pr ttie facing, a .especially ifithe facing material''and the binding. agent consist of the same kind =of= synthetic resin:Since the: binding lagent thus maybe. said toform an integrating part-ofthe facing body and is entirely. plastic during the applica tion of.the' facing to the supporting body and thus :canpenetrateinto allretentionsandirregwlaritiesa :thereimtthe facingwwill after the settingv of thezbinding;agent'ibelimmovablyfandIfirml-y ari chored in thesupporting body.

The. facing, is. suitably? so; shaped that during the application .it ismovable substantially parallel to the main stretch. of. its. contactwith the metallic bodyatleast untillits;

Although acrylic acid has been particularly mentioned as a basicsubstance for a synthetic resin for the present purpose, it will beunderstood that many other plastics are useful than those derivedtherefrom. Thus polystyrene and polyvinylplastics, such aspolyvinylchlorideacetate may be used. Apart from monomerpolymermixturesand chloroform already mentioned, also acetone, methyl ethyl ketone,ethyl acetate and ethylene dichloride as well as, possibly, toluene,benzene, butyl acetate and amyl acetate may come in consideration. Loweralcohols, such as ethyl, methyl and butyl alcohol, and carbontetrachloride, may have some value.

Through this new method of applying a facing it is, on the other hand,rendered possible to make the facing with greater freedom so that guideand anchoring members of the known kind may be dispensed with and thefacing may in lieu thereof be so shaped that, at least during the verygreatest part of'the application to the supporting body, it may beapplied from more or less different directions.

The facing H shown in Figures 1 and 2 is, on its front side l2, shapedas a natural tooth and has at one end a root tip I3, which is intendedfor the cavity after an extracted tooth. On the backside, the facing hasat the top a shoulder M which should be shaped in accordance with thenatural tooth. Between the root tip it and the shoulder M the facing isprovided with a number of grooves or slots and ground-off portionswhich, in the instance shown, leave two elevations 15. Between thesethere is a vertical groove l6, and between the elevations and the roottip there is a horizontal groove or slot ll. These grooves or slots areat right angles to each other and are so disposed as to form a T.Laterally of the elevations the facing is provided with recesses l8.

The supporting body, which in Figure 1 consists of a bridge 2|, isprovided with projections or lamellae, namely 22 extending into thehorizontal groove l1 and 23 extending into the ver tical groove l6.Moreover, the bridge may have lamellae corresponding to the recesses Hi.In certain places or everywhere on its surface, the supporting body hasretentions 24 which preferably are wider inwards than at the mouths andmay consist of projecting flanges or pricks or the like.

In Figures 4 and another embodiment is i1- lustrated in which the bridge2| has projecting beams or lamellae 23 provided with trough-holes 40into which the binding agent can penetrate to form supporting andanchoring beams. The tip I3 is bevelled as indicated at ll for engagingsmoothly the upstanding collar 42 of the bridge. The bridge has threeparallel lamellae 23 and as shown in Figure 5 the facing has threecorresponding grooves or slots It in the cavity 53 over which the roottip l3 and the crown tip it stick out to form seats 44 and 45 for thebridge.

Although the grooves or slots IE5 and I! may widen somewhat inwards,this is not at all necessary but on the contrary disadvantageous, and

it is most often preferable if they taper inwards. However, thesegrooves should conform rather closely with the corresponding projectionsor lamellae 22 and 23, respectively, on the supporting body in orderthat the requisite quantity of binding agent be small. Nevertheless, itis evident that the grooves or slots may be so shaped as to permit thatthe facing ll need not be applied in such a definite direction as in theprior art devices, but far more renders possible an extensive freedom inthe choice of direction of application. However, the innermost portionsof the grooves and the outermost edges of the supporting body should fitaccurately in each other so that the final position becomes fixed.

Figure 6 shows how a facing according to Fig ures 1 and 2 may, by merelygrinding-off the root tip it, be converted into a facing adapted for apivot tooth. The facing of Figures 4 and 5 may, of course, be treatedanalogously. The contour 26 of the root tip and its inner surface 2'!are represented in Figure 3 by means of dot and dash lines. Thesupporting body 30 is, in the same way as the supporting body 2i,provided with retentions 31 but extends, in contrast to the body 2!,farther downwardly towards the root portion, and also there it may haveretentions. In relation to the facing, the body 30 is in other respectsshaped substantially identically with the bridge body 2| so that thesame facing may fit a bridge as well as a pivot.

The supporting body 30 is secured, in accordance with conventionaldental practice, in the tooth root 32 by means of a pivot 33. A mantle3a is tightly secured on the upper edge of the root in the usual manner.

Through the invention it is also made possible to provide the supportingbody with reinforcing beams so that its strength is increased, with aresultant considerable saving of material.

The grooves or slots l6 and I! are preferably at an angle to each other,as shown in Figure 2, but the angle may be of a magnitude other than Thegrooves may also be disposed in a fishbone like manner or crosswise.Further they may depart from the rectilinear form and be, for instance,circular, semicircular or annular. It is essential, however, that theypermit of an application in at least some directions differing more orless from each other. They should also afford supporting surfaces forvertical as well as horizontal pressures.

What is claimed is:

l. A dental prosthesis, comprising, in combination, an elongated toothmember of artificial resin having a front face and a rear face; acut-out arranged in said rear face of said elongated tooth member andhaving a top and bottom face being spaced apart from the top and bottomedges, respectively, of said elongated tooth member and a lateralengagement face provided with at least two elongated recesses thereinarranged substantially normally to said lateral engagement face of saidcut-out and extending parallel to the axis of said elongated toothmember substantially from the top to the bottom face of said cut-out; asupporting metal body including a backing portion fitting into saidcut-out of said elongated tooth member and having a top and bottom edgeand a frontal engagement face located between said edges and engagingsaid lateral engagemerit face of said cut-out; at least two projectinglamellae on said frontal engagement face of said backing portionprojecting substantially normally to said frontal engagement face,extending substantially from said top edge to bottom edge of saidbacking portion and being shaped for entering said elongated recesses insaid lateral engagement face of said cut-out whereby said backingportion of said supporting body and said lamellae thereon can be broughtto engagement with said cut-out and elongatedrecesses,respecmotionithereofbeing.substantiallynormalz to rsaidengagementl-faces of. saidarelong'ated tooth mem ber: and said backinglportiomi andrbinder' means retainingxsaid hackingportioniaandi said ilamellae thereon inlsaid cute.out v.andrelengated recesses,respectivelmfof..saidelongated .itOOth. member;

2. A dental prosthesis, comprising, in combination, an elongated toothmember of artificial resin having a front face and a rear face andhaving at least two elongated recesses in said rear face arrangedsubstantially normally to said rear face and extending parallel to theaxis of said elongated tooth member and spaced from the engaging saidrear face of said elongated tooth member; at least two projectinglamellae on said frontal engagement face of said backing portionprojecting substantially normally to said frontal engagement face,extending said top edge to said bottom ing portion and being shaped forentering said elongated recesses in said rear face of said elongatedtooth member whereby said lamellae on said backing portion of saidsupporting body can be brought to engagement with said elongatedrecesses in the rear face of said elongated tooth member only by amotion thereof being substantially normal to said rear face of saidfacing member; and binder means retaining said lamellae in saidelongated recesses so as to firmly attach said elongated tooth member tosaid backing portion of said supporting body.

3. A dental prosthesis, comprising, in combination, an elongated toothmember having a front face and a rear face; a cut-out arranged in saidrear face of said elongated tooth member and having a top and bottomface being spaced apart from the top and bottom edges, respectively, ofsaid elongated tooth member and a lateral engagement face provided withat least two elongated recesses therein arranged substantially normallyto said lateral engagement face of said cut-out and extending parallelto the axis of said elongated tooth member substantially from the top tothe bottom face of said cut-out; a supporting metal body including abacking portion fitting into said cut-out of said elongated tooth memberand having a top and bottom edge and a frontal engagement face locatedbetween said edges and engaging said of said cut-out, said lateralengagement face top and bottom faces of said cut-out flaring slightlyoutward from said lateral engagement face toward said rear face of saidelongated tooth member; at least two projecting lamellae on said frontalengagement face of said backing portion projecting substantiallynormally to said frontal engagement face, extending substantially fromsaid top edge to sa1d bottom edge of said backing portion and beingshaped for entering said elongated recesses in said lateral engagementface of said cut-out whereby said backing portion of said supportingbody and said lamellae thereon can be brought to engagement with saidcut out and elongated recesses, respectively, of said elongated toothmember only by a motion thereof being substantially normal to saidengagement faces of said elongated tooth member and said backingportion; and binder means retaining said backing portion and saidlamellae thereon in said cut-- having a front face outiand" elongatedrecesses; elongaterlutootmmcmbem 4.2m dehtahprosthesis;comprising, incombinae: tionsan elongated" toothmembenlof artificial resin r and arear face'; acut-outi arranged in said :rear face cf said elongatedtooth member and havin -a nand bottom face being spaced apart from thetop and bottom edges, respeotivelyppf said elo'ngate'd tooth member anda lateral engagement facezproyided-with at least two elongated recessestherein-arranged substan-..-

tially' normally to said lateral LengagementifaCe of said cutout andextending parallel to the axis of said elongated tooth membersubstantially from the top to the bottom face of said cut-out; asupporting metal body including a backing portion fitting into saidcut-out of said elongated tooth member and having a top and bottom edgeand a frontal engagement face located between said edges and engagingsaid lateral engagement face of said cut-out; at least two projectinglamellae on said frontal engagement face of said backing portionprojecting substantially normally to said frontal engagement face,extending substantially from said top edge to said bottom edge of saidbacking portion and being shaped for enterin said elongated recesses insaid lateral engagement face of said cut-out whereby said backin portionof said supporting body and said lamellae thereon can be brought toengagement with said cut-out and elongated recesses, respectively, ofsaid elongated tooth member only by a motion thereof being substantiallynormal to said engagement faces of said elongated tooth member and saidbacking portion; and a binder consisting of a material containingsynthetic resin, said binder filling the portions of said recessesunoccupied by said lamellae and of said cut-out unoccupied by saidbacking portion whereby said supporting metal body and the lamellaethereon are firmly held in said cut-out and the recesses respectively insaid elongated tooth member.

5. A dental prosthesis, comprising, in combina tion, an elongated toothmember of artificial resin having a front face and a rear face andhaving at least two elongated recesses in said rear face arrangedsubstantially normally to said rear face and extending parallel to theaxis of said elongated tooth member and spaced from the top and bottomedges of the same so as to be closed along their tops and bottoms,respectively; a supporting metal body including a backing portion havinga top and bottom edge and a frontal engagement face located between saidedges and engaging said rear face of said elongated tooth member; atleast two projecting lamellae on said frontal engagement face of saidbacking portion projecting substantially normally to said frontalengagement face, extending substantially from said top edge to saidbottom edge of said backing portion and being shaped for entering saidelongated recesses in said rear face of said elongated tooth memberwhereby said lamellae on said backing portion of said supporting bodycan be brought to engagement with said elongated recesses in the rearface of said elongated tooth member only by a motion thereof beingsubstantially normal to said rear face of said facing member, each ofsaid lamellae being formed with at least one retention hole; and abinder consisting of a material containing a synthetic resin, saidbinder penetrating into said retention holes of said lamellae, fillingthe. portions of said recesses unoccupied by said lamellae and of saidrespectively, ofrsaidu References Cited in the file of this patentUNITED STATES PATENTS Name Date Low June 9, 1885 Number Number 675,8811,481,209 2,308,195 2,314,503 2,394,659

8 Name Date Cassullo June 11, 1901 Kauffman Jan. 15, 1924 Morris Jan.12,1943 Kurgas Mar. 23, 1943 Breyer Feb. 12, 1946 Saflir Apr. 16, 1946

